The Mechanism Of Land Use/Cover Change In Lushan Mountain National Nature Reserve Based On Multi-source Data

Lushan Mountain is the "Ecological Intersection Island" on the large plain in the middle and lower reaches of the Yangtze River,and it has preserved a relatively complete ecosystem.Lushan Mountain.As a national key landscape and famous scenery,it is suffering from a disturbance of the long-term human activity,and heavy pressure has been brought to the natural ecosystem.In the nature reserve,vegetation is the main cover type of the reserve,and the vegetation cover has an important influence on the ecological environment of the reserve.It is of great significance for the development of sustainable management measures to understand the spatial and temporal changes of vegetation cover in the nature reserve and to scientifically analyze the relationship between vegetation,climate and human activities.Bamboo roots are more developed and highly expandable,and have a great impact on the growth of surrounding vegetation during the bamboo roots growth process.In recent years,the extension and spread of the bamboo forests of the Lushan Mountains to the surrounding evergreen broad-leaved forests or coniferous and broad-leaved mixed forests is increasingly obvious.The expansion of the bamboos seriously interferes with the surrounding original vegetation,and triggers the fragmentation of forest landscapes,the reduction of biodiversity,the degradation of forest soil,etc.The problem is a serious threat to the stability of the forest ecosystem in Lushan National Nature Reserve and the forest landscape pattern of Lushan Mountain.How to dynamically monitor the spatial and temporal distribution of the forest resources,scientifically recognize the spatial and temporal evolution of the forest landscape and its mechanism,effectively master the distribution and dynamic evolution trends of the forest resources,realize the sustainable management of the forest resources and maintain the function of the forest ecosystem is an important problem and it is urgent to construct demonstration model of forest ecological protection.Based on the theory of the sustainable development,the present investigation took national nature reserve--Lushan National Nature Reserve as the research area,and effectively combined the thirty years of the remote sensing data from 1988 to 2017 with multi-source data such as the survey of the geographical conditions,and the investigation of forestry resource.The spatial database of the basic data elements of the Lushan National Nature Reserve,which was integrated with the natural geographical conditions,the land use/cover changes,the socio-economic development and the forestry survey data was constructed,based on which the spatio-temporal evolution and mechanism of the long time series vegetation in the protected areas were analyzed macroscopically and microscopically.In view of the dynamic monitoring of the coverage of the global forest vegetation in the protected area macroscopically,the eighteen terms of Landsat image data of the Lushan protected area from 1988 to 2017 was processed and analyzed,and the time and space change of thirty years of the normalized differential vegetation index(NDVI)of the protected area were obtained,and the spatial and temporal variation of NDVI in the area was explored.Microscopically,the remote sensing quantitative inversion model of typical vegetation bamboo forest was constructed by combining with the Gaofen-2 satellite and Landsat satellite data,the evolution trend and centroid migration trend of the bamboo forest were obtained.The spatio-temporal evolution law and mechanism of vegetation in the protected areas were revealed based on macro-and micro-analysis and combined with climate,topography,human activities and other driving factors.Based on the above analysis,Establish an NDVI variability and key wild plant protection early warning mechanism,and optimize the boundary of the protected area and the functional area boundary line,which can provide scientific basis for the scientific management and protection measures of the protected area,improve the quality of forest vegetation and the integrity of the ecosystem,and achieve sustainable management of protected areas.The main conclusions of this paper are as follows:(1)Pattern of LUCC spatio-temporal evolutionBased on the long-term sequence of Landsat remote sensing images and sample filed data,the multi-level forest vegetation information is extracted by remote sensing techniques,and the land use classification,NDVI characteristics and spatio-temporal distribution patterns of the bamboo forest information are obtained.The best method is that the quantitative extraction of bamboo forest information of the Gaofen-2 satellite with the support vector machine classification method of texture features,and the bamboo forest classification production accuracy and user precision are more than 90%.Through land use/cover change pattern in Lushan Nature Reserve,forest land,bamboo forest and grassland accounted for more than 80%of the protected area,among which the forest land area continued to rise from 1988 to 2013,and decreased slightly from 2013 to 2017.From the NDVI distribution,the average NDVI value of reserve area in the past 30 years is 0.663.Overall,the NDVI value of the Lushan National Nature Reserve is high in the middle area and low in the surrounding area.The average NDVI value is lower in the surrounding area due to close to the building area and roads.Overall,the area of bamboo forest showed a downward trend,decreasing at a rate of 0.92/a.From the perspective of spatial distribution,the total area of bamboo forest area>experimental area>buffer zone;bamboo forest distribution is the least in the range of 1200-1446 meters,mainly distributed in the range of 400-600 meters and 600-800 meters elevation;bamboo forest in yellow-brown soil has the least distribution,mainly distributed in red soil and yellow soil,among which the proportion of area distributed in red soil is the largest;The distribution area of bamboo forest area on slope type is as follows:normal slope>steep slope>gentle slope>steep slope>flat slope;The distribution area of bamboo forest area on slope direction is as follows:sunny slope>semi-sun slope>semi-shady slope>shady slope.(2)Characteristics of LUCC spatio-temporal evolutionThis paper analyzes the dynamic change and transfer matrix of land use/coverage to analyze the conversion between various land types:the degree of the forest land change was more stable.The change degree of the construction land and the bare land,the bamboo forest and the cultivated land was more intense.The rate of no transformation was more than 90%among forest land from 1988 to 2017.The main transformation types were the bamboo forest and the cultivated land.Construction land and bare land were mainly transformed into woodland and cultivated land;cultivated land was mainly transformed into woodland and bamboo forest;bamboo forest was mainly transformed into forest land and cultivated land.From the point of view of different zoning of the protected area:the degree of core area and buffer zone were close,and the degree of change was small in the comprehensive dynamic degree of the regional land use/cover type change,and the comprehensive dynamic degree of the experimental area was more intense.From different research periods,the comprehensive dynamics of 1988-2013 showed a decreasing trend,and the degree of land use change slowed down.The comprehensive dynamics of 2013-2017 demonstrated a sharp upward trend,and the degree of land use change was more intense.Through a linear regression analysis of NDVI changes,the NDVI in Lushan National Nature Reserve showed a downward trend in the last 30 years as a whole,with a trend decrease of 0.017/10a.The NDVI value decreased from 1988 to 1993,and the NDVI value continued to rise from 1993 to 1996.From 1996 to 2002,NDVI changed less.NDVI fell first and then rose during 2002-2017,and began to rise rapidly after falling to the bottom in 2013.In order to further analyze the NDVI value of long-term sequence change trend of reserve area,the change trend of NDVI was divided into five types through the analysis of coupling Theil-Sen Median trend analysis and Mann-Kendall significance test:slight decrease,significant decrease,significant increase,slight increase and basically unchanged type.The order of the proportion of the five types regions to the total area of the protected area was as follows:slight decrease>slight increase>basic unchanged>significant increase>significant decrease.The results of the variation coefficient of NDVI in Lushan National Nature Reserve from 1988 to 2017 were as follows as a whole:low variation>medium variation>high variation>higher variation>small variation.The proportions of the area of the above regions accounted for the Lushan Nature Reserve were 1.51%,52.54%,31.02%,7.16%and 7.78%,respectively.(3)Driving mechanism of LUCC spatio-temporal evolutionIn this paper,the influence mechanism of spatio-temporal evolution of forest vegetation NDVI is analyzed using methods of univariate linear regression trend,pearson correlation,and spatial superposition coupling.Among the land use/cover change characteristics,the driving factors affecting land use/cover change are mainly human activities.The dynamic changes of land use/cover in core zone and buffer zone as a whole is lower than that in the experimental zone.Among the characteristics of NDVI spatio-temporal evolution,the main influencing factors are elevation and human activities.The mean value of NDVI in reserve areas increases with the increase of elevation.The distribution of NDVI mean value in each functional partition is core zone>buffer zone>experimental zone;The severity of NDVI variability was the shady slope>semi-shady slope>semi-sun slope>sunny slope;the significant change areas of NDVI trend change are mainly distributed in the gentle slopes,and the significant reduction areas are mainly distributed in the core zone with large tourist density and functional partitions.The temperature and the average NDVI change in reserve area have no significant positive correlation with over the years.The rainfall and the average NDVI change in reserve area have no significant negatively correlation with the average NDVI change over the years.Through the weighted centroid model to analyze the changes of bamboo core centroids,the trend and mechanism of bamboo forest centroid evolution in Lushan National Nature Reserve in the past 30 years is the migration to high altitude,low slope and sunny slope.(4)Sustainable management strategy of reserve areaBased on the spatio-temporal evolution mechanism of forest vegetation in reserve areas,the NDVI variability and key wild plant protection early warning mechanism were carried out for the spatio-temporal evolution of forest vegetation in reserve areas,proposing the improvement of forest vegetation quality in reserve areas through three aspects of the dynamic monitoring of forest vegetation spatio-temporal evolution,improving the early warning mechanism of forest vegetation protection,and optimizing the boundary and functional partitions of reserve areas,which can improve the quality of forest vegetation and the integrity of ecosystems,and achieve sustainable management of protected areas.